Arc-extinguishing device



Feb. 22, 1938. .L w. HUFFSTUTTER ARC EXTINGUISHING DEVICE INVENTOR Job?? Af. Huf/staffer:

Original Filed Sept. 20, 1930 'ATTORNEY Patented Feb. 22, 1938 UNITED sTATEs ABC-EXTINGUISHING DEVICE John W. l-Iuilstutter, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application September 20, 1930, Serial No. 483,235 Renewed January 16, 1935 26 Clail'ns.

Another object of my invention is to provide a circuit interrupter with a deionizing device of the above-mentioned type with means for effecltively extinguishing arcs of low current value as well as arcs of high current values.

A further object of my invention is to provide an arc-extinguishing device of the above-mentioned type with a plurality of fibre members disposed about the arc path, which are biased toward each other to conilne the arc but which are held apart by a distance proportional to the amount of pressure developed in the arc stream.

A still further object of my invention is to provide an arc-extinguishing structure of the abovementioned type with a substance that liberates a gas, in the presence of an arc, which is turbulently passed through the arc stream and is conned by the substance in such manner that the amount of gas evolved, and the corresponding pressure of that gas, bear a direct relation to the amount of current present in the arc.

Difiiculty has been experienced in the past in providing a circuit interrupter of the expulsion type that effectively operates to interrupt currents of both high and low values.

When the .decomposition and evolution of a gas from insulating members is depended upon value are found to be incapable of expanding to a suilicient extent along the side walls of the insulating member or of evolving a suiiicient amount of unionized gas. A

AIi it is attempted to overcome this diillculty by reducing the width of the space between the walls, arcs of high current values will develop such destructive pressures that the confining structure will be damaged.

' In practicing my invention, I overcome the above-mentioned diillculties by providing walls of insulating, gas-evolving material that are disposed on opposite sides of an arc path. The walls are pressed toward each other by biasing means which may be adjustable and are held apart by the movable contact member which extends between them when the circuit interrupter is in closed-circuit position. When an arc is drawn because of the separation of the contact members, the passage of the movable contact member from to cool and deionize the arc, arcs of low currentl (Ul. zoo- 147) between the walls causes the walls to be forced into intimate engagement with the arc by the biasing means. The pressure developed in the arc stream thus regulates the width of the slot between the plates, the pressure and slot width being functions of the arc current. In this construction both the resistance of the arc to lateral expansion and the liberation of un-ionized gas are proportional to the current in the arc, and my circuit interrupter successfully extinguishes arcs having either low or high current values.

My invention will best be understood by referring to the following specification taken in conjunction with the accompanying drawing wherein:

Fig. 1 is a sectional view, in elevationiof a circuit-interrupting structure embodying my invention.

Fig. 2 is an enlarged sectional view, in side ele- .vation, of the arc-extinguishing device disclosed in Fig. 1.

Fig. 3 is a front elevational view of the arcextinguishing device shown in Figs. 1 and 2.

Fig. 4 is a bottom end view of a fragment of the arc-extinguishing device shown in Fig. 3.

My invention comprises, in general, an enclosing chamber I for the circuit breaker that is provided with a cover 2 which supports the insulated conductors 3, in a well known manner. The chamber I may be constructed of light material that need not be water-proof if the structure is to be employed within doorsbut which is constructed of heavier, weather-resisting material if the structure is to be employed out of doors. Stationary contact members 4 are supported on the enclosed ends of the conducting bushings 3 and are bridged by the conducting rods 5 and a conducting bar 6 which are supported on a lift rod 1. The lift rod 'I extends through the cover 2 and is actuated to closed and to open positions by a suitable mechanism 8 mounted exterior of the chamber i. Arc-extinguishing and deionizing devices 9 are mounted on the ends of the insulated conductors 3, in the path of movement of the conducting rods 5.

'Ihe arc-extinguishing device 9 is shown enlarged in Figs. 2, 3 and 4 and comprises a rectangular insulating enclosure consisting of a pair of oppositely disposed side members each including an outer side plate il and four inner plates I2, I3, I4 and I5. The plates I2, I3, I l and I5 are separated by pairs of vertical end bars I1 and intermediate bars I8 both of insulating material, and are clamped together by through bolts I9 which are embedded in the plates I2. Side plates II insulate the embedded portion of the bolts I9 and are fastened to the plates I2 and I3 by the screws I6. To facilitate assembly, dowel pins 2I extend through the plates I2, I3, I4 and I5. This construction provides a central opening 22 extending vertically between the side members and closed, at the upper end of the enclosure, by insulating bars 23, which abut, at their inner ends, the stationary contact member 4 to form a gastight seal therewith. Through bolts I9 also extend through the bars 23.

In the space 22, and between the bars I8, are mounted a pair of movable plates 24- made of fibrous insulating material, such as fuller board or the like, that decomposes in the presence of an arc and evolves an un-ionized gas which facilitates extinguishment of the arc in a manner to be hereinafter described. The plates 24 are spaced on opposite sides of the flat movable contact member 5 and are yieldingly pressed toward one another and into contact with the contact member 5 by springs 25 disposed in recesses 26 in the plates I2, I3 and I4 to press against movable insulating bars 21 slidably mounted in rectangular slots 28 in the plates I5. The bars 21 engage the plates 24, for the purpose of moving them toward one another when the contact member 5 is moved downwardly to its open position. The plates 24 are loosely supported upon dowel pins 29. When the contact member 5 is moved downwardly, the springs 25 press the upper ends of the plates 24 inwardly to reduce the volume of the space between the plates. 'I'his movement is opposed by the pressure generated by gases resulting from decomposition of the inner faces of the plates 24 in the presence of the arc. In the event of a low-current arc' the springs will force the plates inward and reduce the volume of the space sufciently to maintain the gas pressure necessary for arc extinguishment and, in the event of a high-current arc, as the gas pressure builds up, it forces the plates 24 outwardly against the force of the springs 25 and prevents excessive pressure,

while, at the same time, it produces a maximum area of contact between the plates and the arc under all pressure conditions. In this manner, a slot or space between the movable plates is varied in width and volume in accordance with the energy of the arc and the resulting pressure developed in the arc stream.

The theory of the narrow-slot method of interrupting a circuit and preventing re-initiation of the arc thereafter, has been set forth in Patent No. 1,958,904 to J. Slepian issued May 15, 1934 and assigned to the assignee of the present invention. When an arc is established between narrow confining insulating members, the expansion of the arc, in the presence of increased arc current, is limited by the side walls, and the arc is forced to expand laterally in the slot between the members. K

After the arc is thus confined by immovable members, the arc voltage no longer decreases in accordance with an increase of current, but remains constant. 'I'he pressure developed between such stationary members, when the arc current` increases to a large value, becomes excessive, and the members may be damaged or destroyed. My present spring-pressed insulating members prevent the deleterious effects caused by excessive pressures and enable my arc-extinguishing device to operate effectively over a large range of current values.

In Patent No. 2,084,979 of J. Slepian, issued June 22, 1937 and assigned to the assignee 0i the present invention, an arc-extinguishing device is disclosed wherein turbulent gases, which are evolved from abutting solid materials, in the presence of an arc, are employed to extinguish and prevent reiinitiation of the arc. Such turbulent gases are developed in my present circuit-interrupter structure and the arc extinguishment is aided, not only by turbulent movement within the arc stream, but also by the confinement of the arc between the insulating members, as set forth in the first-mentioned copending application.

When the pressure required to successfully extinguish an arc and to prevent its re-initiation has been determined by computation or experiment, the number and strength of the springs may be determined, by methods readily evident to persons skilled in the art, to meet the require Y ments of any particular condition. In the device illustrated, six springs are employed and are distributed to apply pressure over a wide area of the surface of the plates II but it is to be understood that the number and strength of the-springs may be varied and the same pressure obtained. Means may be provided for adjusting springs in order to effect a regulation of the pressure on the plates where systems of higher voltage ratings are to be interrupted. As a specific example of one modification of my invention, a circuit interrupter that was successfully operated on a. 13,800 volt system developed a pressure of 50 pounds per square inch upon the plates 24, this pressure being found to be suii'icient to successfully effect interruption of currents ranging from substantially 0 to 3,500 amperes.

In employing certain structures described above, a greater separation of the contact members will be required than in certain cases where stationary plates are employed and thus necessitate a greater length of arc-extinguishing structure, however, the amount of gas developed will be substantially the same per inch length of arc.

The operation of my arc-extinguishing device will now be described. Assume the circuit interrupter to be in the closed position shown in Fig. 2, when the operating mechanism B is released, the lift rod l moves downwardly, carrying the bridging bar 6 and the contact rods 5 downwardly therewith, thereby establishing arcs between the ends of the contact rods 5 and the contact members 4. plates 24 are forced toward each other and into intimate contact with the arc stream. The presence of the arc prevents the members 24 from contacting with each other and, therefore, a space or slot is always present between the two members.

The width of the slot varies in accordance with the amount of current present in the arc, and the arc is, therefore, confined by the members 24 and is permitted to expand in a lateral direction within the slot. The slot itself will only increase in width with a substantial increase in arc current which effects an increase in pressure. The close proximity of the cool surfaces of the members 24 effects recombination of the ions'of the arc stream, and the arc path becomes deionized.

The presenceV of the arc in intimate contact with the bre side walls of the members 24 causes decomposition thereof and liberation of un-ionized gases that pass turbulently through the arc stream. The rapid passage of the gas through the arc stream causes the arc core to become further deionized and contracted until, upon the occurrence of zero current in the course Owing to the bias of the springs 25, the f ionizing device is employed upon an alternatingcurrent circuit) the arc is` extinguished. Because lof the presence of the un-ionized gas, and the close proximity of the side walls oi' the plate members 24, complete deionization of the arc path is en'ected, and the arc \is prevented from re-igniting when the voltage isagain impressed across the contact members 4 and l.

When my arc-extinguishing structure is employed on direct-current circuits. the confining of the arc by the insulating members is regulated in such manner that the arc voltage is greater than the voltage of the system, and the shrinking of the arc core then continues. as the arc stream is deionized by the turbulent gas and the confining members. until the arc' is ilnallv disrupted. 'I'he arc path becomes completely deionized thereaftenthe voltage required to maintain an arc being increased to a value above that of the system. the arc thus beingprevented from igniting after once having been extinguished.

In the case of either alternating or directcurrent circuits. the volume and pressure oi' the gas developed in the arc stream is proportional to the arc energy and. in my arc-interrupting structure, the amount ci' gas evolved is always sufficient. in proportiony to the arc energy, to effect an extinguishment and to prevent arc reinitiation, without being great enough to cause excessive pressures.

In order to prevent hot gases from escaping from the arc-extinguishing structure 9 and efi'ecting insulation breakdowns exterior of the device` I have provided the bottom vents or paths Il for the gas developed with meta-l cooling and deionizing plates 3|. The plates 3i have been described in a copending application of J. Slepian.

Serial No. 333.466 illed Jan. 18. 1929, and assigned the path provided for the moving contact member 5, I have'provided an insulating-deflector 32 having a convex upper side and surrounding the contact rod and supported on the upper edges of the plates 3| in notches 33 provided in'certain of the plates 3| in the vicinity of the deector.

It will thus be seen that I have provided an arc-extinguishing device for a circuit interrupter that is capable of extinguishing arcs of low current Values as Well as those of high current values. My device is effective in extinguishing arc on direct-current circuits as well as on alternating current circuits. In either case, the arc is extinguished in an exceedingly short interval of time because of the employment of both the destanding furnace temperatures without rapidly subliming or gasifying.

While I have described and illustrated a single embodiment of my invention, it will be apparent to those skilled in the art that many changes, additions, omissions, and substitutions may be made therein, without departing from the spirit and scope of my invention as set forth in the accompanying claims.

" I claim as my invention:

1. In an extinguishing device for arcs in air, a gas-evolving solid provided adjacent to the arc path, said gas-evolving solid being movable and biased into intimate engagement with the arc.

2. In an extinguishing device for arcs in air, a pair of plates, at least one of which is made of gas-evolving material, said plates being disposed on opposite sides of the arc path and having biasing means for forcing at least one of the plates toward the other into intimate engagement with an arc, and means for regulating the tension of said biasing means.

3. In an extinguishing device for arcs in air, a pair of plates of gas-evolving material, said plates being disposed on opposite sides of the arc path, biasing means for forcing the plates toward each other, into intimate engagement with an arc, to confine the expansion of the arc in one 'direction and to permit it to expand, under conflnement, in another direction.

4. In an extinguishing device, a pair of plates made of fullerboard, said plates being disposed on opposite sides of the arc path, biasing means for forcing the plates toward each other into intimate engagement with an arc, the distance between the plates being automatically regulated by the pressure developed in the arc.

5. An arc-extinguishing device associated with the separable contact members of a circuit interrupter including gas-evolving plates abutting against the contact members when the latter are in closed-circuit position, means for biasing the plates toward each other, the said plates being moved toward each other by the biasing means when the contacts are separated to draw an arc. the distance of the plates from each other during arc establishment depending on the amount of current in the arc.

6. The method of extinguishing an arc including the steps of drawing an arc in air, subjecting the arc to a mechanical pressure and envolving a gas and passing it turbulently through the arc stream.

7. The method of extinguishing an arc including the steps of drawing an arc in air, subjecting the arc to a mechanical. compressive force and evolving an arc-extinguishing gas in an amount proportional to the current of the arc and passing it laterally into the arc. l y

8. The method of extinguishing an arc including the steps of drawing an arc in air, subjecting the arc to a'mechanical compressive force and evolving an arc extinguishing gas in an amount proportional to the current of the arc and passing the gas turbulently through the arc stream.

9. 'Ihe combination with separable contact members of a. circuit interrupter having means for confining an arc .established thereby between walls of fullerboard, of means for biasing one of the walls toward the other to coni'lne the arc, the proximity of the walls to each other being a function ofthe arc current.

10. In an extinguishing device for arcs in air, gas-evolving members disposed about the arc stream, said members being biased toward each other but held apart by the gas evolved a distance proportional to the amount of gas pressure developed by the arc.

11. In a circuit interrupter of the air-brake type, an arcing chamber having laterally expanslble walls of gas evolving material.

12. In a circuit breaker having relatively movable contacts, an arc-confining chamber for said contacts having Walls that-collapse inwardly toward each other as one of said contacts is moved to open position.

13. In a circuit breaker having relatively movable contacts, an arc-confining chamber for said contacts having walls that collapse inwardly toward each other as one of said contacts is moved to open position and that are expansible outwardly in response to gas pressure generated by the arc within the chamber.

14. In an extinguishing device for arcs in air a chamber surrounding the arc, said chamber having members adjacent the arc of a material which gives off a gas under action of the arc, and means for causing the cross-section of said chamber in a direction transverse to the arc to vary in response to the amount of gas generated by the arc.

15. An a circuit interrupter of the air-brake type, a pair of members of material which evolves a gas when acted upon by an arc, conducting means for initiating an arc positioned between said members, said means causing the arc to play between said pair of gas evolving members and longitudinally therealong, and said gas evolving members being movable transversely to the arc in response to the pressure of the gas evolved.

16. In a circuit interrupter, an expulsion chamber closed on four sides and open to a gaseous atmosphere at one end, means within said chamber for evolving a gas in the precence of an4 arc, conducting means extending longitudinally through said chamber adjacent said gas evolving means for causing an arc, and means for causing the cross-section of said chamber to vary with the pressure developed by the deionizing gas.

17. In a circuit interrupter, an expulsion chamber closed on four sides and open at one end, a movable member in said chamber constructed of fullerboard, means for causing an arc in said chamber, said movable member being acted upon by the gas due to said arc to vary the size of said chamber to provide a large chamber for heavy current arcs and a small chamber for small current arcs.

18. In a circuit interrupter, an expulsion chamber closed on four sides and open to a gaseous atmosphere at one end, a pair of relatively movable members in said chamber constructed of material which gives off a gas in the presence of an arc, a conducting member between said pair of relatively movable members for causing an arc and being movable out of said chamber and leaving a space between said relatively movable members in which the arc plays, the Width of said space being greater for heavy current arcs than for small current arcs.

'19. In an extinguishing device for arcs in air, a gas-evolving insulating solid positioned adjacent to the arc path, said solid being movable and biased into intimate engagement with the arc.

20. Tn an extinguishing device for arcs in air, a gas-evolving insulating substance about the arc path, and biasing means for forcing said substance into intimate contact with the arc stream.

21. In an extinguishing device for arcs in air,

a pair of insulating plates, at least one of which is made of a gas-evolving material, said plates being disposed on opposite sides of the arc path and means for forcing at least one of the plates toward the other into intimate engagement with the arc.

22. In an arc-extinguishing device, a plurality of walls, at least one of which is made of fullerboard, said walls being disposed on opposite sides of the arc path, and means for forcing at least one of said walls toward the other into intimate engagement with the arc.

23. In a circuit breaker having relatively movable contacts, an arc-confining chamber for said contacts having walls that collapse inwardly toward each other as one of said contacts is moved to open position, and means for causing a flow of iiuid through the arc and out of said chamber to aid in extinguishing the arc.

24. In a circuit breaker having relatively movable contacts, an arc-conning chamber for said contacts, means included in said chamber which when acted upon by the arc gives oil' gas to aid in extinguishing the arc, said chamber having walls that collapse inwardly toward each other as one of said contacts is moved to open position and that are expansible outwardly in response to gas pressure generated by the arc within the chamber, and venting means permitting the gas to flow expulsively from the chamber.

25. In an extinguishing device for arcs in air, a chamber surrounding the arc, said chamber having members adjacent the arc of a material which gives oiI a gas under action of the arc, and means for causing the cross-section of said chamber in a direction transverse to the arc to be smaller during the extinguishing of arcs carrying low currents than during the extinguishing of arcs carrying heavy currents.

26. In a circuit interrupter, an expulsion chamber closed on four sides and open to a gaseous atmosphere at one end, means within said chamber for evolving a gas in the presence of an arc, conducting means extending longitudinally through said chamber adjacent said gas envolving means for causing an arc, and means for causing the cross-section of said chamber to be smaller during the extinguishing of arcs carrying low currents than during the extinguishing of arcs carrying heavy currents.

JOHN W. HUFTSTU'I'I'ER. 

